Toxicology E3R Practice Exam

Nerve agents and many organophosphate pesticides share the same mechanism: they inhibit acetylcholinesterase, the enzyme that breaks down acetylcholine. War gas is an organophosphorus compound that irreversibly phosphorylates AChE, so acetylcholine keeps accumulating at nerve endings and muscarinic and nicotinic receptors are overstimulated. This leads to the characteristic cholinergic crisis seen with these agents.

Other pesticide classes act differently. Organochlorines disrupt neural signaling through different targets (not AChE inhibition but effects on membranes and other receptors). Carbamates also inhibit acetylcholinesterase but do so reversibly, unlike organophosphates. Pyrethroids affect sodium channels in neurons, prolonging depolarization in a distinct way. So the organophosphorus mechanism best fits nerve agents, including war gas.